Contactor, contact structure provided with contactors, probe card, test apparatus, method of production of contact structure, and production apparatus of contact structure

ABSTRACT

A probe card having a plurality of silicon finger contactors contacting pads provided on a tested semiconductor wafer and a probe board mounting the plurality of silicon finger contactors on its surface, wherein each silicon finger contactor has a base part on which a step difference is formed, a support part with a rear end side provided at the base part and with a front end side sticking out from the base part, and a conductive part formed on the surface of the support part, each silicon finger contactor mounted on the probe board so that an angle part of the step difference formed on the base part contacts the surface of the probe board.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a contactor, a contact structureprovided with contactors, a probe card, a test apparatus, a method ofproduction of a contact structure, and a production apparatus of acontact structure for contacting pads, electrodes, leads, or othercontacts provided on an integrated circuit or other electrical circuit(hereinafter also referred to representatively as an “IC”) formed on aIC semiconductor wafer, semiconductor chip, semiconductor devicepackage, printed circuit board, etc. to establish electric contact withthe ICs when testing the ICs.

2. Description of the Related Art

A large number of semiconductor integrated circuit chips are formed on asilicon wafer etc., then are diced, wire bonded, packaged, and otherwiseprocessed to produce finished electronic devices. These ICs are alltested for operation before shipment. This IC testis performed both inthe finished product state and in the wafer state.

When testing ICs in the wafer state, as a probe for securing electriccontact with a tested IC, there has been known one having a base parthaving inclinations at its two ends, a beam part with a rear end sideprovided at the base part and with a front end side sticking out fromthe base part, and a conductive part formed on the surface of the beampart (hereinafter referred to simply as a “silicon finger contactor”)(for example, see Japanese Patent Publication (A) No. 2000-249722,Japanese Patent Publication (A) No. 2001-159642, and WO03/071289pamphlet).

This silicon finger contactor is formed by for example photolithographyor other semiconductor production technology from a silicon substrate.In particular, when forming the inclinations at the two ends of the basepart, the silicon substrate is anistropically etched so as to forminclined surfaces of 54.7° dependent on the crystal plane of silicon.Further, these inclined surfaces are used to give a predetermined anglefor the silicon finger contactor to be mounted on the probe board.

When using a probe card provided with such silicon finger contactors totest ICs, the probe card is brought close to the semiconductor wafer andthe silicon finger contactors are brought into contact with the pads ofthe tested ICs. Further, the silicon finger contactors are made to movefurther toward the pads (overdriven) so that the front ends of thesilicon finger contactors scrub the pads so as to remove the aluminumoxide layers formed on the pads and thereby establish electric contactwith the tested ICs.

At the time of contact of the silicon finger contactors and pads,variations of the silicon finger contactors in the height directioncause certain silicon finger contactors on the probe board to contactthe pads of the ICs first, then the first contacting silicon fingercontactors are excessively overdriven until all of the silicon fingercontactors provided on the probe board contact the pads of the ICs.

Here, the angles of inclination formed at the base parts of the siliconfinger contactors are relatively sharp angles of 54.7° as explainedabove, so the amount of scrubbing of the silicon finger contactors withrespect to the amount of overdrive of the silicon finger contactorsfirst contacting the pads become large (that is, the amount ofscrubbing/amount of overdrive becomes large). For that reason, forexample, if the size of the pads of the ICs become small, the front endsof the silicon finger contactors end up sticking out from the pads ordeforming or becoming damaged.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a contactor, a contactstructure provided with the contactors, a probe card, a test apparatus,a method of production of a contact structure, and a productionapparatus of a contact structure able to prevent mistaken contact withcontacts.

(1) To achieve the above object, according to the present invention,there is provided a contactor for establishing electric contact with adevice under test when testing the device under test by means ofcontacting a contact provided at the device under test, having a basepart formed with a step difference, a support part with a rear end sideprovided at the base part and a front end side sticking out from thebase part, and a conductive part formed at the surface of the supportpart and electrically contacting the contact, wherein an angle part ofthe step difference formed at the base part contacts the surface of acontact board mounting the contactor so as to thereby define apredetermined inclination angle between the surface of the contact boardand the support part.

In the present invention, the base part of the contactor is formed witha step difference, and this step difference is utilized to mount thecontactor on the contact board in an inclined state. Due to this, it ispossible to control the ratio of the length and depth of the stepdifference so as to mount the contactor on the contact board at adesired angle, so for example even if an IC pad is small in size,mistaken contact with the pad can be prevented.

Note that in the present invention, the “rear end side” in the contactormeans the side contacting the contact board. As opposed to this, the“front end side” in the contactor means the side contacting the contactof the device under test.

While not particularly limited in the above invention, preferably thestep difference has a shape with a height of the rear end side of thebase part relatively lower than a height of the front end side.

While not particularly limited in the above invention, preferably thebase part is formed with a plurality of step differences in a stairwaystate.

Due to this, the support points of the contactor mounted on the contactboard increase, so the stability of attachment of the contactor withrespect to the contact board is improved.

While not particularly limited in the above invention, preferably thesupport part has an insulation layer at the surface on the side wherethe conductive part is formed. The insulation layer is preferablycomprised of SiO₂.

(2) To achieve the above object, according to the present invention,there is provided a contact structure provided with a plurality ofcontactors as set forth in any of the above and a contact board mountingthe plurality of contactors on its surface, wherein each of thecontactors has a plurality of the support parts, and the plurality ofsupport parts are arranged on a single base part at predeterminedintervals.

While not particularly limited in the above invention, preferably thecontactors are bonded to the contact board using an ultraviolet curingtype adhesive, temperature curing type adhesive, or thermoplasticadhesive.

While not particularly limited in the above invention, preferably thecontact board is provided on its surface with a plurality of connectiontraces and the connection traces are electrically connected tocorresponding conductive parts of the contactors.

While not particularly limited in the above invention, preferably theconnection traces provided on the contact board and the conductive partsof the contactors are connected by bonding wires.

(3) To achieve the above object, according to the present invention,there is provided a contact structure as set forth in any one of theabove, wherein the devices under test are electrical circuits formed ona semiconductor wafer, and the contact board has a heat expansioncoefficient (α1) satisfying the following equation (1).α1=α2×Δt2/Δt1   equation (1)

where, in the above equation (1), α1 is a heat expansion coefficient ofthe contact board, Δt1 is a rising temperature of the contact board atthe time of a test, α2 is a heat expansion coefficient of thesemiconductor wafer, and Δt2 is a rising temperature of thesemiconductor wafer at the time of the test.

In the present invention, since the contact board is designed to satisfythe above equation (1), a distance not affecting the impedance issecured between the contact structure and semiconductor wafer and theamounts of expansion of the contact board and semiconductor wafer at thehigh temperature state are matched.

Due to this, the difference between the amount of heat expansion of thecontact board and the amount of heat expansion of the semiconductorwafer at the high temperature state can be made smaller and mistakencontact with pads or other contacts can be prevented. Further, since thedifference of the amounts of heat expansion is made smaller, a widerrange of the semiconductor wafer can be simultaneously tested and agreater number of simultaneous measurements can be secured.

While not particularly limited in the above invention, preferably thecontact board is provided with a core part having a core insulationlayer containing a carbon fiber material, at least one first multilayerinterconnect part having a first insulation layer containing a glasscloth and first interconnect patterns and laminated on the core part,and at least one second multilayer interconnect part having a secondinsulation layer and second interconnect patterns and laminated on thefirst multilayer interconnect part.

Due to this, the heat expansion of the contact board can be kept low, sothe difference between the amount of heat expansion of the contact boardand the amount of heat expansion of the semiconductor wafer at the hightemperature state can be made small.

While not particularly limited in the above invention, preferably thesecond multilayer interconnect part is a builtup layer.

(4) To achieve the above object, according to the present invention,there is provided a test apparatus provided with a test head on which acontact structure as set forth in any of the above is mounted and atester for testing devices under test through the test head.

While not particularly limited in the above invention, preferably thedevices under test are electrical circuits formed on a semiconductorwafer, and the contact structure is mounted on the test head so that aprobe height plane formed by the front ends of the plurality ofcontactors is substantially parallel with the surface of thesemiconductor wafer.

Due to this, variation of the contactors mounted on the contact board inthe height direction can be suppressed.

(5) To achieve the above object, according to the present invention,there is provided a method of production of a contact structure forestablishing electric contact with devices under test when testing suchdevices under test, comprising a feed step of feeding an SOI wafer, abase part formation step of forming etching mask patterns on the bottomsurface of the SOI wafer and etching the bottom surface to form baseparts of contactors having step differences, a support part formationstep of forming etching mask patterns on the top surface of the SOIwafer, etching the top surface, forming etching mask patterns on thebottom surface of the SOI wafer, etching said bottom surface andremoving an SiO₂ layer of the SOI wafer to thereby form support parts ofthe contactors, a conductive part formation step of covering a topsurface of the support parts by a conductive material so as to formconductive parts of the contactors, and a mounting step of mounting thecontactors on a contact board so that angle parts of the stepdifferences formed on the base parts contact the surface of the contactboard.

While not particularly limited in the above invention, preferably thetop surface of the SOI wafer is etched, then an SiO₂ layer forming aninsulation layer is formed on the top surface of the SOI wafer in thesupport part formation step and the surface of the insulation layer iscovered with a conductive material in the conductive part formationstep.

While not particularly limited in the above invention, preferably deepreactive ion etching (DRIE) is used to etch the bottom surface of theSOI wafer in the base part formation step and DRIE is used to etch thetop surface of the SOI wafer in the support part formation step.

While not particularly limited in the above invention, preferably theSOI wafer is a two-layer SOI wafer having two Si layers and one SiO₂layer sandwiched between the two Si layers, and an etching time iscontrolled to form the base parts with the step differences in the basepart formation step.

While not particularly limited in the above invention, preferably theSOI wafer is a three-layer SOI wafer having three Si layers and two SiO₂layers sandwiched between each two of the three Si layers, the SiO₂layer at the bottom side is used as an etching stopper in the base partformation step, and the two SiO₂ layers are removed in the support partformation step.

While not particularly limited in the above invention, preferably themounting step has an arrangement step of bonding the base parts on thesurface of the contact board by a adhesive to arrange the contactors onthe contact board at predetermined inclinations and a connection step ofconnecting connection traces provided on the contact board with thecontactors.

While not particularly limited in the above invention, preferably theconnection traces provided on the contact board and the conductive partsof the contactors are connected by bonding wires in the connection step.

(6) To achieve the above object, according to the present invention,there is provided a production apparatus of a contact structureproducing a contact structure for establishing electric contact withdevices under test when testing the devices under test, comprising acoating means for coating a adhesive at a predetermined position of acontact board, a suction means for holding a contactor by suction, and amoving means for making the contact board move relative to thecontactor, the suction means having a suction surface for contacting thecontactor and applying suction, the suction surface being provided witha limiting means for limiting fine movement of the contactor relative tothe suction surface.

In the present invention, a limiting means is provided for limiting finemovement of the contactor at the suction surface of the suction meansmounting a contactor at a predetermined position coated with a adhesiveon the contact board. Due to this, a contactor can be positioned at andbonded to a predetermined position on the contact board with a highprecision, so mistaken contact at the time of a test can be prevented.

While not particularly limited in the above invention, preferably thesuction surface is an inclined surface having an inclination anglesubstantially the same as the attachment angle of the contactor withrespect to the contact board. Further, preferably the limiting meansinclude a step difference formed on the suction surface. Further,preferably a rear end of said contactor engaged with the stepdifference.

While not particularly limited in the above invention, preferably theapparatus is further provided with a detecting means for detecting arelative position of the contactor with respect to the contact board,and the moving means makes the contactor move so that the contactor donot press against the contact board based on the results of detection ofthe detecting means.

Due to this, when the suction means move the contactor and places it onthe contact board, the contactor can be prevented from pressing againstthe contact board and the contactor can be prevented from finely movingand deviating from the suction surface of the suction means.

(7) To achieve the above object, according to the present invention,there is provided a probe card for establishing electric contact withdevices under test when testing such devices under test, provided with acontactor for contacting a plurality of pads provided at the devicesunder test and a contact board mounting the contactor on its surface,the contactor having a predetermined plurality of elastically deformablelong support parts forming a group, and a single base part on which thegroup of support parts are provided, a rear end side of the base partbeing formed with a step difference defining a predetermined inclinationangle of the support parts with respect to the contact board, the basepart being bonded to the contact board at the rear endside so that thearray of the group of support parts corresponds to the array of theplurality of pads.

While not particularly limited in the above invention, preferably thecontactor has conductive parts formed on at least one side surface ofthe support parts and electrically contacting the pads at those frontend parts, the contact board is provided on its surface with connectiontraces, and the conductive parts and the connection traces areelectrically connected by bonding wires.

While not particularly limited in the above invention, preferably thecontact board is comprised of a board material having a heat expansioncorresponding to the heat expansion of a semiconductor wafer formed withsaid device under test.

(8) To achieve the above object, according to the present invention,there is provided a test apparatus provided with a probe card as setforth in any of the above, a test head on which the probe card ismounted, and a tester for testing the device under test through the testhead.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of the present invention willbecome clearer from the following description of the preferredembodiments given with reference to the attached drawings, wherein:

FIG. 1 is a schematic view of a test apparatus according to the firstembodiment of the present invention;

FIG. 2 is a conceptual view of the connection relationship of a testhead and probe card used in the test apparatus of FIG. 1;

FIG. 3 is a cross-sectional view of a probe card according to the firstembodiment of the present invention;

FIG. 4 is a partial bottom view of the probe card shown in FIG. 3;

FIG. 5 is a partial cross-sectional view along the line V-V of FIG. 3;

FIG. 6 is a cross-sectional view of a silicon finger contactor in thefirst embodiment of the present invention;

FIG. 7 is a plan view of the silicon finger contactor shown in FIG. 6;

FIG. 8 is a view of the state of the silicon finger contactor shown inFIG. 6 mounted on a probe board;

FIG. 9 is a cross-sectional view of a silicon finger contactor in asecond embodiment of the present invention;

FIG. 10 is a cross-sectional view of a first step for producing asilicon finger contactor in the first embodiment of the presentinvention;

FIG. 11 is a cross-sectional view of a second step for producing asilicon finger contactor in the first embodiment of the presentinvention;

FIG. 12 is a cross-sectional view of a third step for producing asilicon finger contactor in the first embodiment of the presentinvention;

FIG. 13 is a cross-sectional view of a fourth step for producing asilicon finger contactor in the first embodiment of the presentinvention;

FIG. 14 is a cross-sectional view of a fifth step for producing asilicon finger contactor in the first embodiment of the presentinvention;

FIG. 15A is a cross-sectional view of a sixth step for producing asilicon finger contactor in the first embodiment of the presentinvention;

FIG. 15B is a plan view of a sixth step for producing a silicon fingercontactor in the first embodiment of the present invention;

FIG. 16 is a cross-sectional view of a seventh step for producing asilicon finger contactor in the first embodiment of the presentinvention;

FIG. 17 is a cross-sectional view of an eighth step for producing asilicon finger contactor in the first embodiment of the presentinvention;

FIG. 18 is a cross-sectional view of a ninth step for producing asilicon finger contactor in the first embodiment of the presentinvention;

FIG. 19 is a cross-sectional view of a 10th step for producing a siliconfinger contactor in the first embodiment of the present invention;

FIG. 20 is a cross-sectional view of an 11th step for producing asilicon finger contactor in the first embodiment of the presentinvention;

FIG. 21 is a cross-sectional view of a 12th step for producing a siliconfinger contactor in the first embodiment of the present invention;

FIG. 22 is a cross-sectional view of a 13th step for producing a siliconfinger contactor in the first embodiment of the present invention;

FIG. 23 is a cross-sectional view of a 14th step for producing a siliconfinger contactor in the first embodiment of the present invention;

FIG. 24 is a cross-sectional view of a 15th step for producing a siliconfinger contactor in the first embodiment of the present invention;

FIG. 25 is a cross-sectional view of a 16th step for producing a siliconfinger contactor in the first embodiment of the present invention;

FIG. 26 is a cross-sectional view of a 17th step for producing a siliconfinger contactor in the first embodiment of the present invention;

FIG. 27 is a cross-sectional view of a 18th step for producing a siliconfinger contactor in the first embodiment of the present invention;

FIG. 28 is a cross-sectional view of a 19th step for producing a siliconfinger contactor in the first embodiment of the present invention;

FIG. 29 is a cross-sectional view of a 20th step for producing a siliconfinger contactor in the first embodiment of the present invention;

FIG. 30 is a cross-sectional view of a 21st step for producing a siliconfinger contactor in the first embodiment of the present invention;

FIG. 31A is a plan view showing a silicon wafer for simultaneouslyproducing a large number of silicon finger contactors in the firstembodiment of the present invention and their cutting positions (part1);

FIG. 31B is a plan view showing a silicon wafer for simultaneouslyproducing a large number of silicon finger contactors in the firstembodiment of the present invention and their cutting positions (part2);

FIG. 31C is a plan view showing a silicon wafer for simultaneouslyproducing a large number of silicon finger contactors in the firstembodiment of the present invention and their cutting positions (part3);

FIG. 32 is a cross-sectional view of a silicon finger contactor in thethird embodiment of the present invention;

FIG. 33 is a schematic view of the overall configuration of a productionapparatus for a probe card according to an embodiment of the presentinvention;

FIG. 34 is an enlarged view of the part XXXIV of FIG. 33 in the statenot holding a silicon finger contactor; and

FIG. 35 is an enlarged view of the part XXXIV of FIG. 33 in the stateholding a silicon finger contactor.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Below, embodiments of the present invention will be described based onthe drawings.

FIG. 1 is a schematic view of a test apparatus according to the firstembodiment of the present invention; while FIG. 2 is a conceptual viewof the connection relationship of a test head and probe card used in thetest apparatus of FIG. 1.

The test apparatus 1 according to the present embodiment, as shown inFIG. 1, is provided with a tester 60 (test apparatus body) having a testhead 10 and a wafer prober 70. The test head 10 is connected through acable bundle 61 to the tester 60. The test head 10 and wafer prober 70are, for example, mechanically positioned and mechanically andelectrically connected by a manipulator 80 and drive motor 81. Thetested semiconductor wafer 200 is automatically fed by the wafer prober70 to a test position on the test head 10.

On the test head 10, the tested semiconductor wafer 200 receives a testsignal issued by the tester 60. Further, an output signal with respectto that test signal is sent from each IC of the tested semiconductorwafer 200 to the tester 60 where it is compared with the expected valueto verify that the IC on the tested semiconductor wafer 200 isfunctioning normally.

In FIG. 1 and FIG. 2, the test head 10 and the wafer prober 70 areconnected via an interface part 20. The interface part 20 is comprisedof a relay board 21, coaxial cables 22, and a frog ring 23. The testhead 10 is provided with a large number of printed circuit boards 11corresponding to the test channels. This large number of printed circuitboards 11 corresponds to the number of test channels of the tester 60.These printed circuit boards 11 have connectors 12 for connecting withthe corresponding contact terminals 21 a on the relay board 21. Further,for accurate determination of the contact positions with respect to thewafer prober 70, a frog ring 23 is provided on the relay board 21. Thefrog ring 23 has a large number of ZIF connectors, pogo pins, or otherconnection pins 23 a. These connection pins 23 a are connected via thecoaxial cables 22 to the contact terminals 21 a on the relay board 21.

Further, as shown in FIG. 2, the test head 10 is arranged on the waferprober 70 and mechanically and electrically connected via an interfacepart 20 to the water prober 70. In the wafer prober 70, the testedsemiconductor wafer 200 is held on a chuck 71. A probe card 30 isprovided above the tested semiconductor wafer 200. The probe card 30 hasa large number of silicon finger contactors 50 for contacting the pads210 of the ICs on the tested semiconductor wafer 200 at the time of atest (see FIG. 3).

The connection terminals of the probe card 30 (not shown) areelectrically connected to the connection pins 23 a provided on the frogring 23. These connection pins 23 a are connected to the contactterminals 21 a of the relay board 21, while the contact terminals 21 aare connected via the coaxial cables 22 to the printed circuit boards 11of the test head 10. Further, the printed circuit boards 11 are, forexample, connected through the cable bundle 61 having several hundredinternal cables to the tester 60.

In the above configured test apparatus 1, the silicon finger contactors50 contact the surface of the semiconductor wafer 200 on the chuck 71,supply test signals to the semiconductor wafer 200, and receive outputsignals from the semiconductor wafer 200. The output signals (responsesignals) from the tested semiconductor wafer 200 are compared with theexpected values at the tester 60 whereby whether the ICs on thesemiconductor wafer 200 are functioning normally is verified.

FIG. 3 is a cross-sectional view of a probe card according to the firstembodiment of the present invention; FIG. 4 is a partial bottom view ofthe probe card shown in FIG. 3; FIG. 5 is a partial cross-sectional viewalong the line V-V of FIG. 3; FIG. 6 is a cross-sectional view of asilicon finger contactor in the first embodiment of the presentinvention; FIG. 7 is a plan view of the silicon finger contactor shownin FIG. 6; and FIG. 8 is a view of the state of the silicon fingercontactor shown in FIG. 6 mounted on a probe board.

The probe card according to the first embodiment of the presentinvention 30, as shown in FIG. 3, is provided with a probe board 40 madeof a multilayer wiring board, a plurality of silicon finger contactors50 mounted on the bottom surface of the probe board 40, and a stiffener35 with the probe board 40 attached to the bottom.

First, the probe board 40 forming part of the probe card 30 will beexplained.

The probe board 40 the present embodiment, as shown in the same figure,is provided with a baseboard 41 having a multilayer structure comprisedof a core part 42 and multilayer interconnect parts 43, and builtupparts 44 formed laminated on the two surfaces of the base board 41. Thebase board 41 is formed with through hole vias 41 a extending in thatthickness direction.

The core part 42 is made from a sheet of carbon fiber reinforced plastic(CFRP) and has a CFRP part 42 a and insulating plastic parts 42 b. TheCFRP part 42 a is comprised of a carbon fiber material and a plasticmaterial containing this and hardened.

The carbon fiber material is a carbon fiber cloth woven from carbonfiber yarn comprised of bundles of carbon fibers and is oriented laidout in the planar direction of spread of the core part 42. A pluralityof the thus configured carbon fiber materials are stacked in thethickness direction and embedded in a plastic material. Note that as thecarbon fiber material, instead of carbon fiber cloth, carbon fiber meshor a carbon fiber nonwoven fabric may also be used.

As the plastic material containing the carbon fiber material, forexample, polysulfone, polyether sulfone, polyphenyl sulfone,polyphthalamide, polyamidimide, polyketone, polyacetal, polyimide,polycarbonate, modified polyphenylene ether, polyphenylene oxide,polybutylene terephthalate, polyacrylate, polysulfone, polyphenylenesulfide, polyether ether ketone, tetrafluoroethylene, epoxy, cyanateester, bismaleimide, etc. may be mentioned.

The insulating plastic parts 42 b are for securing electrical insulationbetween the carbon fiber materials of the CFRP parts 42 a and thethrough hole vias 41 a. As the material forming the insulating plasticparts 42 a, for example, polysulfone, polyether sulfone, or another ofthe above plastic materials may be mentioned.

The multilayer interconnect parts 43 are members in which wirings arestacked in multiple layers by the so-called package lamination methodand have multilayer structures of insulation layers 42 a andinterconnect patterns 42 b. Each insulation layer 42 a is formed using aprepreg comprised of glass cloth impregnated with a plastic materialwhich is then cured. As the plastic material forming the insulationlayers 42 a, for example, polysulfone, polyether sulfone, or another ofthe above-mentioned plastic materials may be mentioned. The interconnectpatterns 42 b are made of for example copper and have their respectivedesired shapes. The interconnect patterns 42 b are mutually electricallyconnected through the through hole vias 41 a.

The builtup parts 44 are parts comprised of multiple layers ofinterconnects formed by the so-called buildup method and have multilayerstructures of the insulation layers 44 a and interconnect patterns 44 b.Each insulation layer 44 a is for example made of polysulfone, polyethersulfone, or another of the above-mentioned plastic materials. Theinterconnect patterns 44 b are made of for example copper and have theirrespective desired shapes. The interconnect patterns 44 b are mutuallyelectrically connected through the through hole vias 44 e. The topmostinterconnect patterns 44 b of the builtup parts 44 are formed withconnection terminals (not shown) to which the connection pins 23 a ofthe frog ring 23 are connected.

Each builtup part 44, as shown in FIG. 5, is formed with a groundpattern 44 c at a layer different from the interconnect patterns 44 b.In the present embodiment, in addition to this, grounded dummy groundpatterns 44 d are formed between the interconnect patterns 44 b. Due tothis, the pattern density of the inside layers of the probe board 40 canbe made uniform, and variations in thickness, warping, etc. of the probeboard 40 can be prevented. Note that FIG. 3 does not show the groundpattern 44 c or the dummy ground patterns 44 d.

The through hole vias 41 a are for mutually electrically connecting theinterconnect structures provided at the two sides of the baseboard 41,that is, the interconnect structures of the interconnect patterns 43 bof the multilayer interconnect parts 43 and the interconnect patterns 44b of the builtup parts 44. The through hole vias 41 a are formed bycopper plating the inner circumferential surfaces of the through holes41 b formed passing through the base board 41. Note that instead of thiscopper plating or in addition to this copper plating, conductive pastecontaining silver powder or copper powder may also be filled in thethrough holes 41 b to form the through hole vias. Note that as thethrough hole vias 41 a, surface via hole (SVH) types may also be used inaddition to through types.

In the present embodiment, as shown in FIG. 3, at the outer sides of thecore part 42, two multilayer interconnect parts 20 are laminated facingeach other. Further, at the outsides of the two multi layer interconnectparts 43, two builtup parts 44 are laminated facing each other, wherebya probe board 40 is formed.

By making the layer configuration of the probe board 40 symmetrical inthe vertical direction, the warping of the probe board 40 itself can bereduced.

Further, the probe board 40 in the present embodiment has a heatexpansion coefficient (α1) satisfying the following equation (1):α1=α2×Δt2/Δt1   equation (1)

where, in the above equation (1) α1 is a heat expansion coefficient ofthe probe board 40, Δt1 is a rising temperature of the probe board 40 atthe time of a test, α2 is a heat expansion coefficient of the testedsemiconductor wafer 300, and Δt2 is a rising temperature ofsemiconductor wafer 300 at the time of the test. Note that Δt1 and Δt2satisfy the following equations (2) and (3).Δt1=T1−Tr   equation (2)Δt2=T2−Tr   equation (3)

where, in the above equations (2) and (3), T1 is the temperature of theprobe board 40 at the time of the test (test temperature setting), T2 isthe temperature of the tested semiconductor wafer 200 at the time of thetest, and Tr is room temperature. Note that T2 is determined by the heatradiated from the tested semiconductor wafer 200 and the heat conductedfrom the silicon finger contactors 50, so can be calculated based on thenumber of the silicon finger contactors 50 mounted on the probe board40.

By the probe board 40 having the heat expansion coefficient satisfyingthe above equation (1), the amounts of expansion of the probe board 30and the tested semiconductor wafer 200 in the high temperature state canbe matched. As a result, the difference between the amount of heatexpansion of the probe board 40 and the amount of heat expansion of thetested semiconductor wafer 200 in the high temperature state can bereduced. Therefore, the positional deviation between the silicon fingercontactors 50 and pads of the ICs is greatly reduced and as a resultmistaken contact is prevented. Further, by making the difference of theamounts of heat expansion smaller, the silicon finger contactors 50 canbe arranged for a wide range of the tested semiconductor wafer 200 and alarge number of ICs can be simultaneously tested, so a greater number ofsimultaneous measurements can be secured.

Next, the silicon finger contactors 50 of the probe card 30 will beexplained.

Each silicon finger contactor 50 in the present embodiment, as shown inFIG. 6, has a base part 51 formed with a step difference 52, a supportpart 53 with a rear end side provided at the base part 51 and a frontend side sticking out from the base part 51, and a conductive part 54formed on the surface of the support part 53.

Note that in the present embodiment, the “rear end side” in a siliconfinger contactor 50 indicates the side contacting the probe board 40(left side in FIG. 6). As opposed to this, the “front end side” in thesilicon finger contactor 50 indicates the side contacting a pad 210 ofan IC formed at the tested semiconductor wafer 200 (right side in FIG.6).

This silicon finger contactor 50, as explained later, is produced from asilicon substrate by photolithography or other semiconductor productiontechnology. As shown in FIG. 7, a single base part 51 is provided with aplurality of support parts 53 in finger shapes (a comb shape). Byarranging the support parts 53 spaced from each other in this way, thesupport parts 53 can operate independently from each other. Further,since a single base part 51 has a plurality of support parts 53 fastenedto it, even narrow pitch IC pads can be easily fabricated and handlingas a unit module is possible. Therefore, mounting on a probe cardbecomes easy and accurate positioning becomes easy.

Further, by using semiconductor production technology to produce thecontactors 50, the pitch of the plurality of support parts 53 can beeasily made the same as the pitch of the pads 210 of the testedsemiconductor wafer 200.

Further, semiconductor production technology may be used to make thecontactors 50 small in size, so a probe card with a good quality ofwaveform in a frequency range of operation of the probe card 30 of 500MHz or more can be realized.

Further, due to the smaller size of the contactors 50, the number ofcontactors mounted on a probe card 30 can be increased to for example2000 or more and the number of simultaneous measurements can beincreased.

The step difference 52 formed at the base part of a silicon fingercontactor 50, as shown in FIG. 6, has a shape with the height of therear end side made relatively lower than the height of the front endside at the base part 51. This step difference 52 has the depth H andlength L.

Each of the support parts 53 is formed on it with an insulation layer 53a for electrically insulating the conductive layer 54 from the otherparts of the silicon finger contactor 50. This insulation layer 53 a is,for example, comprised of an SiO₂ layer or a boron-doped layer.

The surface of each insulation layer 53 a is formed with a conductivepart 54. The material forming the conductive part 54 may be nickel,aluminum, copper, gold, nickel cobalt, nickel palladium, rhodium, nickelgold, iridium, or other depositable materials. Note that the front endof the conductive part 54 is preferably made a sharp shape. Due to this,the scrubbing effect at the time of contact of the silicon fingercontactors 50 and the pads 210 can be enhanced. The above configuredsilicon finger contactors 50, as shown in FIG. 3, are mounted on theprobe board 40 so as to face the pads 210 of the ICs formed on thetested semiconductor wafer 200. Note that FIG. 3 only shows two siliconfinger contactors 50, but in actuality a large number of silicon fingercontactors 50 are arranged on the probe board 40.

Each silicon finger contactor 50, as shown in FIG. 8, is bonded to theprobe board 40 so that the angle parts 52 a, 52 b of the step difference52 formed on the base part 51 contact the surface of the probe board 40.As the adhesive for bonding a silicon finger contactor 50 and probeboard 40, for example, an ultraviolet curing type adhesive, temperaturecuring type adhesive, thermoplastic adhesive, etc. may be mentioned.Note that the base part 51 is wide in area, so a sufficient bondstrength is obtained.

In the present embodiment, the step difference 52 formed on the basepart 51 is used to mount the silicon finger contactor 50 on the probeboard 40, so the silicon finger contactor 50 is inclined with respect tothe probe board 40 by an angle β corresponding to the ratio of the depthH and length L of the step difference 52.

That is, in the probe card 30 according to the present embodiment, bycontrolling the ratio of the depth H and length L of the step difference52, a silicon finger contactor 50 can be easily mounted on the probeboard 40 by a desired accurate angle β of for example 54.7° or less. Dueto this, the ratio of the amount of scrubbing with respect to the amountof overdrive of the first contacting silicon finger contactors 50(amount of scrubbing/amount of overdrive) can be reduced, so even if thepads 210 of the tested semiconductor wafer 200 are made small in size,mistaken contact with the pads 210 can be prevented.

Note that the inclination angle β of a silicon finger contactor 50 withrespect to the probe board 40 is preferably as small as possible, but ifthis angle β is too low, the contactor is liable to abut against acapacitor etc. provided on the probe board 40.

As shown in FIG. 3 and FIG. 4, the bottom surface of the probe board 40is provided with connection traces 40 a. The connection traces 40 a areelectrically connected through the bonding wires 40 b to the conductiveparts 54 of the silicon finger contactors 50. Further, the connectiontraces 40 a are electrically connected to vias 44 e provided at thebottom most layer of the bottom builtup part 44 of the probe board 40.Note that instead of the bonding wires 40 b, solder balls may also beused to electrically connect the connection traces 40 e and conductiveparts 44.

As shown in FIG. 3, the probe board 40 on which the silicon fingercontactors 50 are attached is attached to a stiffener 35. At this time,shims etc. are inserted between the probe board 40 and stiffener 35 toadjust the probe height plane PL formed by the front ends of all of thesilicon finger contactors 50 mounted on the probe board 40 to becomesubstantially parallel to the surface of the tested semiconductor wafer200 and then the probe board 40 is attached to the stiffener 35. Due tothis, variation of the silicon finger contactors 50 mounted on the probeboard 40 in the height direction can be suppressed.

In the test using the above configured probe card 30, when the testedsemiconductor wafer 200 moves over the probe card 30, the silicon fingercontactors 50 on the probe board 40 and the pads 210 on the testedsemiconductor wafer 200 are mutually mechanically and electricallyconnected. As a result, signal paths are formed from the pads 210 to theconnection terminals (not shown) formed at the topmost positions of theprobe board 40. Note that the narrow pitches of the silicon fingercontactors 50 are fanned out to large distances through the connectiontraces 40 a and interconnect patterns 43 b, 44 b of the probe board 40.

When the silicon finger contactors 50 contact the pads 210, since thesilicon finger contactor 50 are mounted on the probe board 40 inclined,the long support parts 53 elastically deform. Due to this elasticdeformation, the front ends of the conductive parts 54 scrub the metaloxide films formed on the surfaces of the pads 210, whereby electriccontact between the silicon finger contactors 50 and pads 210 isestablished. Here, the length, width, and thickness of the support parts53 are determined based on the required pressing force to the pads 210and the required amounts of elastic deformation.

FIG. 9 is a cross-sectional view of a silicon finger contactor in asecond embodiment of the present invention.

The silicon finger contactor 50′ in the second embodiment of the presentinvention is formed with a plurality of the step differences 52′ in astaircase shape. Due to this, the support points of the silicon fingercontactors 50 mounted on the probe board 40 increase, so the stabilityof attachment of the silicon finger contactor 50 with respect to theprobe board 40 is improved.

Below, one example of the method of production of the probe card 30according to the present embodiment will be explained.

FIG. 10 to FIG. 30 are views of steps for producing a silicon fingercontactor in the first embodiment of the present invention, while FIG.31A to FIG. 31C are plan views showing a silicon wafer forsimultaneously producing a large number of silicon finger contactors inthe first embodiment of the present invention and their cuttingpositions.

In the present embodiment, photolithography or other semiconductorproduction technology is used to form a large number of pairs of siliconfinger contactors 50 on a silicon substrate 55, then the pairs ofcontactors 50 are separated.

In the method of production according to the present embodiment, in thefirst step shown in FIG. 10, first, an SOI wafer 55 is prepared. This SOwafer 55 is a two-layer SOI wafer having two Si layers 55 a at the topand bottom and one SiO₂ (silicon dioxide) layer 55 b sandwiched betweenthe two Si layers 55 a. The SiO₂ layer 55 b of this SOI wafer 55functions as an etching stopper when forming the support parts 53.

Next, in the second step shown in FIG. 11, a SiO₂ (silicon dioxide)layer 57 is formed on the bottom surface of the SOI wafer 55. This SiO₂layer 57 functions for forming the etching mask patterns when formingthe step differences 52 at the base parts 51.

Next, in the third step shown in FIG. 12, the SiO₂ layer 57 is formedwith a resist layer 56 a. In this step, while not particularlyillustrated, first the SiO₂ layer 57 is formed with a photoresist film,then this photoresist film is overlaid with a photomask and is exposedby ultraviolet light and cured, whereby parts of the SiO₂ layer 57 areformed with a resist layer 56 a. Note that the parts of the photoresistfilm not exposed by ultraviolet light are dissolved and washed away fromthe SiO₂ layer 57. This resist layer 56 a is used in the next fourthstep as the etching mask patterns.

Next, in the fourth step shown in FIG. 13, the SiO₂ layer 57 formed onthe bottom of the SOI wafer 55 is etched using, for example, reactiveion etching (RIE) etc. After this etching is completed, at the fifthstep shown in FIG. 14, the resist layer 56 a is removed.

Next, in the sixth step shown in FIG. 15A, the SOI wafer 55 is formed onits top surface with a resist layer 56 b. This resist layer 56 b isprocessed by the same procedure as the above-mentioned third step, asshown in FIG. 15B, to form finger shapes (a comb shape) on the topsurface of the SOI wafer 55.

Next, in the seventh step shown in FIG. 16, the upper Si layer 55 a ofthe SOI wafer 55 is etched. As this etching technique, the DRIE methodmay be mentioned. This etching is used to form the upper Si layer 55 aof the SOI wafer 55 into finger shapes (a comb shape). At this time, theSiO₂ layer 55 b of the SOI wafer 55 functions as an etching stopper.After this etching is completed, in the eighth step shown in FIG. 17,the resist layer 56 b is removed.

Next, in the ninth step shown in FIG. 18, the top surface of the SOIwafer 55 is formed with an SiO₂ layer 53 a. This SiO₂ layer 53 afunctions as an insulation layer of the support parts 53.

Next, in the 10th step shown in FIG. 19, the same procedure as theabove-mentioned third step is used to form a resist layer 56 c on partof the bottom surface of the SOI wafer 55 and on the SiO₂ layer 57.

Next, in the 11th step shown in FIG. 20, the Si layer 55 a at the bottomof the SOI wafer 55 is etched. As a specific technique of this etching,the DRIE similar to the seventh step may be mentioned. Due to thisetching, the bottom Si layer 55 a is removed to exactly a depth h. Thisdepth h is set by controlling the etching time in the DRIE. When thisetching is completed, in the 12th step shown in FIG. 21, the resistlayer 56 c removed.

Next, in the 13th step shown in FIG. 22, the SiO₂ layer 53 a formed onthe top surface of the SOI wafer 55 is formed above it with a seed layer54 a made of gold and titanium. As the technique for forming this seedlayer 54 a, vacuum deposition, sputtering, vapor deposition, etc. may bementioned.

Next, in the 14th step shown in FIG. 23, the same procedure as theabove-mentioned third step is used to form a resist layer 56 d on partof the seed layer 54 a.

Next, in the 15th step shown in FIG. 24, the seed layer 54 a is platedwith nickel cobalt to form a nickel cobalt film 54 b. After this platingis completed, the resist layer 56 d is removed in the 16th step shown inFIG. 25.

Next, in the 17th step shown in FIG. 26, the same procedure as theabove-mentioned third step is used to form a resist layer 56 e on partof the nickel cobalt film 54 b.

Next, in the 18th step shown in FIG. 27, the nickel cobalt film 54 b isplated with gold to form a gold plating film 54 c. After this plating iscompleted, the resist layer 56 e is removed in the 19th step shown inFIG. 28.

Next, in the 20th step shown in FIG. 29, the front end part of the seedlayer 43 a is removed, then in the 21st step shown in FIG. 30, thebottom Si layer 55 a of the SOI wafer 55 is etched. As a specific methodof this etching, the DRIE method similar to the seventh step may bementioned. At this time, the SiO₂ layer 57 formed at the bottom surfaceof the SOI wafer 55 and the SiO₂ layer 55 b of the SOI wafer 55 functionas etching stoppers. This etching further removes the bottom Si layer 55a by exactly the depth H to form the step difference 52 of the base part51. This depth H is set by controlling the etching time in DRIE.

Next, in the 22nd step, the SiO₂ layer 57 formed on the bottom surfaceof the SOI wafer 55 and the SiO₂ layer 55 b of the SOI wafer 55 areremoved by dry etching, whereby the silicon finger contactors 50 such asshown in FIG. 6 are completed. At this time, due to the removal of theSiO₂ layer 55 b of the SOI wafer 55, a space is formed between thesupport parts 53.

Next, the SOI wafer 55 on which the silicon finger contactors 50 areproduced is cut by dicing for example along the line A-A, line B-B, andline C-C shown in FIG. 31A. That cut SOI wafer 55 is, as shown in FIG.31B, further cut as needed for each group of silicon finger contactors50. That is, as shown in FIG. 31C, as shown in FIG. 31B, the SOI wafer55 is further cut along the line D-D and the line E-E so that apredetermined number of silicon finger contactors 50 is provided foreach group.

Next, predetermined positions of the probe board 40 are coated with aadhesive, the thus produced silicon finger contactors 50 are placed atthe predetermined positions, and the silicon finger contactors 50 arebonded to the probe board 40. At this time, the silicon fingercontactors 50 are placed on the probe board 40 so that the angle parts52 a, 52 b of the step differences 52 formed at the base parts 51contact the surface of the probe board 40. Due to this, the siliconfinger contactors 50 are attached to the probe board 40 at aninclination angle β according to the ratio of the depth H and length Lof the step differences 52.

Further, the connection traces 41 a provided at the probe board 40 andthe conductive parts 54 of the silicon finger contactors 50 areconnected by bonding wires 41 b to complete the probe card 30 accordingto the present embodiment.

FIG. 32 is across-sectional view of a silicon finger contactor in thethird embodiment of the present invention.

The silicon finger contactor 50″ of the third embodiment of the presentinvention is basically comprised of a three-layer SOI wafer having threeSi layers 55 a and two SiO₂ layers 55 b sandwiched between the three Silayers.

In the present embodiment, when forming the step difference 52 of thebase part 51″, instead of controlling the etching time, it is possibleto use the bottom SiO₂ layer 55 b of the SOI wafer as an etching stopperto set the depth H of the step difference 52 to a high precision.

Note that in the present embodiment, in the etching of the Si layer 55 afrom the bottom surface of the SOI wafer for forming the support parts53, the bottom SiO₂ layer 55 b of the SOI wafer must be removed.

Below, a production apparatus for a probe card according to anembodiment of the present invention will be explained.

FIG. 33 is a schematic view of the overall configuration of a productionapparatus for a probe card according to an embodiment of the presentinvention; FIG. 34 is an enlarged view of the part XXXIV of FIG. 33 inthe state not holding a silicon finger contactor; and FIG. 35 is anenlarged view of the part XXXIV of FIG. 33 in the state holding asilicon finger contactor.

The probe card production apparatus 100 according to an embodiment ofthe present invention is a apparatus for mounting silicon fingercontactors 50 produced by the above-mentioned FIG. 10 to FIG. 31C on aprobe board 40.

This probe card production apparatus 100, as shown in FIG. 33, isprovided with a suction unit 131 for holding a silicon finger contactor50 by suction, a coating unit 132 for coating a predetermined positionon the probe board 40 with a adhesive 45, a measurement unit 134 formeasuring the relative height of a silicon finger contactor 50 withrespect to the probe board 40, a camera unit 140 for recognizing theposition or posture of the probe board 40 and silicon finger contactor50, and a movement stage 150 for making the probe board 40 move relativeto the silicon finger contactor 50.

The suction unit 131 has at its front end a suction surface 131 a forcontacting and sucking on the top surface of a silicon finger contactor50. This suction surface 131 a, as shown in FIG. 34, is formed by aninclined surface having an angle substantially the same as the angle βof attachment of the silicon finger contactor 50 to the probe board 40.

This suction surface 131 a has opened at it one end of a passage 131 bpassing through the suction unit 131. The other end of this passage 131b, as shown in FIG. 33, is communicated with a vacuum pump 120.

Further, in the present embodiment, the suction surface 131 a, as shownin FIG. 34 and FIG. 35, is formed with a step difference 131 c withwhich the rear end of the silicon finger contactor 50 engages.

Due to this, the silicon finger contactor 50 held by the suction unit131 can be restricted from fine movement with respect to the suctionsurface 131 a. As a result, the silicon finger contactor 50 can bepositioned and bonded to a predetermined position on the probe board 40with a high precision, so mistaken contact at the time of the test canbe prevented.

As opposed to this, when one suction surface 131 a is not formed withthe step difference 131 c, the surface tension of the adhesive 45 actsagainst the suction force of the suction unit 131, the silicon fingercontactor 50 slides along the suction surface 131 a, and the siliconfinger contactor 50 is liable to be bonded to the probe board 40 in thestate deviated from its predetermined position.

Returning to FIG. 33, the coating unit 132 is a syringe for ejecting anultraviolet curing type adhesive on the probe board 40. This coatingunit 132 is provided with an ultraviolet emission unit 133 for curingthe adhesive 45 coated on the probe board 40.

The measurement unit 134 has, for example, a noncontact type distancemeasurement sensor using a laser etc. The distance measurement sensorcan measure the distance between a silicon finger unit 50 held by thesuction unit 131 and the probe board 40, that is, the height of thesilicon finger unit 50 with respect to the probe board 40.

The suction unit 131, coating unit 132, and measurement unit 134 areattached to an elevation head 130. This elevation head 130 is supportedby a frame 110 provided surrounding the movement stage 150 on which theprobe board 40 is held and is designed to be able to move in the Z-axisdirection with respect to the movement stage 150.

The camera unit 140 has, for example, a CCD camera provided so as to beable to capture images below it. This camera unit 40 is attached to theframe 110 independently of the elevation head 130 and can move in theXY-direction.

The movement stage 150 has a chuck (not shown) able to hold the probeboard 40 and can make that probe board 40 move in the X-axis directionand Y-axis direction and can make the probe board 40 rotate about theZ-axis in the θ direction.

In the above configured probe card production apparatus 100, the probecard 30 is produced as follows.

First, the camera unit 140 captures an image of the probe board 40 heldon the movement stage 150 and recognizes the relative position of theprobe board 40 with respect to the elevation head 130. Further, themovement stage 150 moves so that a predetermined position of the probeboard 40 faces a discharge port of the coating unit 132, then theelevation head 130 descends in the Z-axis direction.

The coating unit 132 coats the adhesive 45 at a predetermined positionon the probe board 40, then the camera unit 140 captures an image of thesilicon finger contactor 50 held by the suction head 131 and theposition and posture of the silicon finger contactor 50 are recognized.

Next, the movement stage 150 is moved so that the silicon fingercontactor 50 held by the suction unit 131 is positioned above apredetermined position of the probe board 40, then the elevation head130 descends in the Z-axis direction.

At the time of this descent, the measurement unit 134 measures theheight of the silicon finger unit 50 with respect to the probe board 40.Further, when the height of the silicon finger contactor 50 with respectto the probe board 40 becomes zero, the measurement unit 134 stops thedescent of the elevation head 130 in the Z-axis direction. Due to this,the silicon finger contactor 50 can be prevented from being pushedagainst the probe board 40. As opposed to this, if the silicon fingercontactor 50 is pushed against the probe board 40, that pressing forceis liable to cause the silicon finger contactor 50 to slide along theinclination of the suction surface 131 a, so the silicon fingercontactor 50 is liable to be bonded to the probe board 40 in a statedeviated from the predetermined position.

After the silicon finger contactor 50 is placed at a predeterminedposition on the probe board 40, the movement stage 150 is moved so thatthe front end of the ultraviolet emission unit 133 faces thepredetermined position. Then, the ultraviolet emission unit 133 emitsultraviolet light to cure the adhesive 45 and bond the silicon fingercontactor 50 at the predetermined position on the probe board 40.

By repeating the above routine for each of the group of silicon fingercontactors 50 shown in FIG. 31C, a large number of silicon fingercontactors 50 are mounted on a single probe board 40.

Note that the above embodiments were described to facilitateunderstanding of the present invention and were not described to limitthe present invention. Therefore, the elements disclosed in the aboveembodiments include all design changes and equivalents falling withinthe technical scope of the present invention.

1. A contact structure comprising: a plurality of contactors forestablishing electric contact with devices under test when testing thedevices under test by means of contacting a contact provided at thedevices under test, and a contact board mounting said plurality ofcontactors on its surface, wherein each of said plurality of contactorsincludes: a base part formed with a step difference, a plurality ofsupport parts, each of the plurality of support parts having a rear endside provided at the base part and a front end side sticking out fromthe base part, wherein said plurality of support parts are arranged onsaid base part at predetermined intervals, and a conductive part formedat the surface of at least one of the plurality of support parts andelectrically contacting the contact, wherein an angle part of the stepdifference formed at the base part contacts the surface of the contactboard mounting the plurality of contactors so as to thereby define apredetermined inclination angle between the surface of the contact boardand each of the plurality of support parts, and wherein said devicesunder test are electrical circuits formed on a semiconductor wafer, andsaid contact board has a heat expansion coefficient (α1)satisfying thefollowing equation (1):α1=α2×Δt2/Δt1  equation (1) where, in the above equation (1), α1 is aheat expansion coefficient of said contact board, Δt1 is a risingtemperature of said contact board at the time of a test, α2 is a heatexpansion coefficient of said semiconductor wafer, and Δt2 is a risingtemperature of said semiconductor wafer at the time of the test.
 2. Acontact structure as set forth in claim 1, wherein said contact board isprovided with a core part having a core insulation layer containing acarbon fiber material, at least one first multilayer interconnect parthaving a first insulation layer containing a glass cloth and firstinterconnect patterns and laminated on said core part, and at least onesecond multilayer interconnect part having a second insulation layer andsecond interconnect patterns and laminated on said first multilayerinterconnect part.
 3. A contact structure as set forth in claim 2,wherein said second multilayer interconnect part is a builtup layer. 4.A contact structure for establishing electric contact with electricalcircuits formed on a semiconductor wafer when testing said electricalcircuits, provided with a plurality of contactors for contactingcontacts provided on said electrical circuits and a contact boardmounting said plurality of contactors on its surface, said contact boardhaving a heat expansion coefficient (α1)satisfying the followingequation (1):α1=α2×Δt2/Δt1  equation (1) where, in the above equation (1), α1 is aheat expansion coefficient of said contact board, Δt1 is a risingtemperature of said contact board at the time of a test, α2 is a heatexpansion coefficient of said semiconductor wafer, and Δt2 is a risingtemperature of said semiconductor wafer at the time of the test.
 5. Acontact structure as set forth in claim 4, wherein said contact board isprovided with a core part having a core insulation layer containing acarbon fiber material, at least one first multilayer interconnect parthaving a first insulation layer containing a glass cloth and firstinterconnect patterns and laminated on said core part, and at least onesecond multilayer interconnect part having a second insulation layer andsecond interconnect patterns and laminated on said first multilayerinterconnect part.
 6. A contact structure as set forth in claim 5,wherein said second multilayer interconnect part is a builtup layer. 7.A probe card having a contact structure as set forth in claim
 5. 8. Atest apparatus provided with: a test head on which a contact structureas set forth in claim 5 is mounted and a tester for testing devicesunder test through said test head.
 9. A test apparatus as set forth inclaim 8, wherein said devices under test are electrical circuits formedon a semiconductor wafer, and said contact structure is mounted on saidtest head so that a probe height plane formed by the front ends of saidplurality of contactors is substantially parallel with the surface ofsaid semiconductor wafer.